Trev,
Book yourself an
F1 drive (not ride), my wife gave this to me for my birthday last year, Good fun!
Warwick Castle is always worth a look.
Imperial War Museum at Duxford is a day well spent.
There's a shop in Stratford Upon Avon has a shop that sells authentic magic wands(!) and other really cool Harry Potter stuff (yes we had children in tow)
Cheers